A video digital recording/reproducing apparatus (hereinafter, referred to as “video disc recorder”) using a disc medium has begun to be pervasive. Required is a technique for realizing, at an inexpensive price, an after-recording function in such a video disc recorder, as is the case with a tape medium. The after-recording function refers to a technique for further adding information, especially audio information, to recorded audio information and/or recorded video information.
A conventional technique for realizing such an after-recording function using a disc medium was provided by the present inventors, and is disclosed in Japanese Laid-Open Patent Publication Tokukai 2001-43616 (published on Feb. 16, 2001). The following briefly explains this technique with reference to FIG. 20(a) and FIG. 20(b).
In Japanese Laid-Open Patent Publication Tokukai 2001-43616, a stream file 3000 is in compliance with a unique stream format, and is so structured that regions for storing the after-recorded data are inserted among original stream data (initially recorded video/audio data) divided at a predetermined reproduction time interval. The after-recorded data is reproduced in synchronism with the original stream data. For example, FIG. 20(a) illustrates that an after-recording data region 3011 for storing after-recorded audio data that is to be reproduced in synchronism is inserted just before partial original stream data 3021. Likewise, after-recording data regions 3012 and 3013 are inserted just before partial original stream data 3022 and 3023, respectively.
The stream file 3000 is recorded onto an optical disc 3001 such that each set of partial original stream data and each after-recording data region are disposed physically adjacent to each other as shown in FIG. 20(b). This minimizes seeking operation during the synchronous reproduction of the partial original stream data and the after-recorded data, and restrains interruption of the reproduction due to the seeking operation. Further, a real-time after-recording is ensured by setting reproduction time of the partial original stream data to such a value (roughly several seconds) that allows for the real-time after-recording and that is determined in consideration of a seeking time.
Incidentally, examples of widely used data recording method are: Transport Stream (hereinafter, referred to as “MPEG-2 TS”) and Program Stream (hereinafter, referred to as “MPEG-2 PS”), each of which has a different structure from the stream structure described in Japanese Laid-Open Patent Publication Tokukai 2001-43616, and each of which is defined by ISO/IEC 13818-1. For example, MPEG-2 PS is used for DVD-Video, and MPEG-2 TS is used for a data transfer format between devices by way of digital broadcasting or the IEEE-1394. Conventional after-recording techniques in consideration of MPEG-2 PS/TS are described in Japanese Laid-Open Patent Publication Tokukai 2000-306327 (published on Nov. 2, 2000), and Japanese Laid-Open Patent Publication Tokukaihei 11-298845/1999 (published on Oct. 29, 1999).
However, in cases where the stream structure described in Japanese Laid-Open Patent Publication Tokukai 2001-43616 is applied to MPEG-2 PS/TS, a general decoder possibly cannot normally carry out decoding for reproduction. A reason for this is explained as follows.
It is determined in MPEG-2 TS/PS that video data and audio data are multiplexed such that no underflow and no overflow occur in respective buffer memories of an audio decoder and a video decoder that are in compliance with a decoder model set as a standard (reference). However, in the stream structure of Japanese Laid-Open Patent Publication Tokukai 2001-43616, audio data corresponding to one second or longer is stored in each of the after-recording data regions. When such a stream file is reproduced by using a general MPEG-2 TS/PS decoder, the MPEG-2 TS/PS decoder receives, at a time, the audio data corresponding to one second or longer. This causes overflow of the buffer memory of the audio decoder.
Further, according to the after-recording function described in Japanese Laid-Open Patent Publication Tokukai 2000-306327, the after-recording data region is multiplexed in the stream in accordance with the aforementioned MPEG-2 PS multiplexing rule; however, the after-recording function suffers from a difficulty in the real-time after-recording when a transfer rate to or from a disc is low.
On the other hand, in Japanese Laid-Open Patent Publication Tokukaihei 11-298845/1999, the after-recorded data and the original stream data are recorded onto different files such that each of the files is in compliance with the MPEG-2 PS multiplexing rule. In this case, a file containing the after-recorded data and a file containing the original stream data are alternately read out, so that a seeking operation is required to be repeated during the reproduction of the after-recorded result. For this reason, when a non-destructive editing is carried out with respect to the after-recorded result, the seeking operation is more likely to cause interruption of reproduction especially between scenes. The non-destructive editing refers to an editing that is virtually carried out by using reproduction route information instead of using the stream data on a disc. Moreover, the technique is also disadvantageous in power consumption.
The present invention is made in light of the problem, and its object is to provide a data recording method that allows reproduction and real-time after-recording in a general MPEG-2 PS/TS decoder, and allows less interruption of reproduction when a non-destructive edit is carried out with respect to an after-recorded result.